function valid(form) {
  var field = form.email;
  var str = field.value;
  if (window.RegExp) {
    var reg1str = "(@.*@)|(\\.\\.)|(@\\.)|(\\.@)|(^\\.)";
    var reg2str = "^.+\\@(\\[?)[a-zA-Z0-9\\-\\.]+\\.([a-zA-Z]{2,3}|[0-9]{1,3})(\\]?)$";
    var reg1 = new RegExp(reg1str);
    var reg2 = new RegExp(reg2str);
    if (!reg1.test(str) && reg2.test(str)) {
      return true;
    }
    field.focus();
    field.select();
    return false;
  } else {
    if(str.indexOf("@") >= 0)
      return true;
    field.focus();
    field.select();
    return false;
  }
}